Filled polymeric materials have been known to provide decorative and protective surfaces to walls. For instance, it has been known to coat masonry units filled with polyesters and to form walls therefrom. The basic patent on the use of polyester as coatings for masonry units is U.S. Pat. No. 2,751,775 to Sergovic and assigned to the assignee of the present application. Over the years a number of improvements in the coating compositions for the masonry building units have been developed. For instance, U.S. Pat. No. 3,328,231 to Sergovic and assigned to the assignee of the present application, discloses a glazed masonry building block made of a cured composition of an unsaturated polyester and sand in which the sand comprises at least 50% by weight of the coating composition. The unsaturated polyester is derived from a reaction between a dicarboxylic acid, such as phthalic, maleic, fumaric, adipic, pimelic, suberic, itaconic, citraconic, succinic acids and/or an anhydride thereof, and a polyhydric alcohol such as ethylene glycol, diethylene glycol and propylene glycol. Also present in such compositions, is an unsaturated monomer such as methyl methacrylate, styrene, diallyl phthalate, t-butyl styrene and alphamethyl styrene.
Furthermore, U.S. Pat. No. 4,031,289 to Sergovic discloses coated masonry blocks, articles and compositions therefore that employ various pigments in combination with various resinous compositions to provide stain resistance when subjected to high moisture conditions and/or staining media. The disclosures of the above-mentioned U.S. Pat. Nos. 2,751,775; 3,328,231; and 4,031,289, as well as U.S. Pat. Nos. 4,329,822 and 2,817,619 are incorporated herein by reference.
More recently, there have been some disclosures concerning texturing or providing a pattern onto a glazed building unit such as the methods disclosed in U.S. Pat. No. 4,533,568 to McClinton and U.S. Pat. No. 4,956,200 to Malkowski, and assigned to the assignee of the present application, disclosures of which are incorporated herein by reference. However, although the methods disclosed in U.S. Pat. Nos. 4,533,568 and 4,956,200 are satisfactory for the most part, the processes disclosed therein are somewhat limited in the types of patterns and surface texture that can be achieved and create surface textures and appearances that are quite different from the pleasing relief designs possible with the instant invention. For example, the methods disclosed in these patents are not particularly suitable for providing well-defined patterns having relatively narrow raised or lowered portions. Moreover, the methods described in these U.S. patents are not especially suitable for providing distinct patterns, designs or logos that project out from the glazed surface rather than being depressed therein.
The traditional method in the industry for over 30 years of creating relief patterns in a mold has been very limited and has been accomplished through expensive bending, welding, shaping and spinning of metal to form very simple patterns and the steel has then been coated and fired with a uniform layer of enamel but the cost to produce a single mold is as high as several hundred dollars and the mold pattern cannot be changed once the metal is formed.